高原世居藏族青少年最大运动时氧代谢动力学特点

目的：了解青藏高原世居藏族青少年运动负荷下的氧代谢动力学特点,以探讨高原环境对青少年健康的影响。方法：对海拔４２００ｍ高原２０例健康世居藏族及１５例同龄移居汉族青少年的氧代谢动力学指标进行测定,包括最大氧耕量、血氧饱和度和心指数等。结果：世居藏族青少年的最大负荷、无氧代谢阈值、最大心指数、最大氧供给量和最在氧耕量、血氧饱和度均明显大于移居组（Ｐ〈０．０５或Ｐ〈０．０１）;两组各项指标在运动前后的变     

高原慢性缺氧对不同民族促红细胞生成素的影响

[目的]探讨高原慢性缺氧对不同民族健康男性血清促红细胞生成素(EPO)的影响机制. [方法]用双抗体夹心ABC-ELISA法对高原移居汉族和世居藏族健康男性血清EPO水平进行测定.同时用放射免疫法测定血清肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6). [结果]世居藏族血清EPO含量明显高于移居汉族(P＜0.01);TN-α高于移居汉族(P＜0.05);IL-6世居藏族高于移居汉族,但无统计学差异(P=0.13). [结论]高原慢性缺氧使世居藏族血清EPO明显高于移居汉族.     

增氧呼吸器在不同海拔高度下对血氧饱和度和心率的影响

目的：探讨增氧呼吸器在高原不同海拔环境下对机体血氧饱和度和心率的影响;方法：140名受试者分别在高原（海拔3 700,3 750,3 950,4 700,4 900,5 300m）进行运动负荷实验,首先检测静息状态下不使用仪器的血氧饱和度（blood oxygen saturation,SaO2）和心率.而后进行运动负荷实验（不佩戴增氧呼吸器）,检测数据,并检测1,2,3min的恢复心率和血氧饱和度.24h后佩戴仪器后,重复以上检测;结果：静息状态下,与不使用单兵高原增氧呼吸器的试验结果相比较,在高原不同海拔环境下使用增氧呼吸器后,SaO2明显增加,心率明显降低,其差异具有统计学意义（P＜0.05）.运动负荷实验结束后,佩戴增氧呼吸器后在3 750,3 950,4 900m的高度下机体SaO2明显升高,差异特别显著（P＜0.01）;结论：增氧呼吸器在高原不同海拔高度下能有效地提高和改善士兵的军事作业能力,而且效果显著,对高原习服有明显的促进作用.     

高原健康人运动状态下最大氧耗量 无氧代谢阈值及心功能变化的特点

在海拔3417m地区测定了藏汉族少年的最大氧耗量及无氧代谢阈.结果:最大耗氧量藏族大于汉族(P<0.05),无氧阈汉族低于藏族(P<0.01).血氧饱和度随运动负荷的增加而下降,达到最大负荷时藏族下降8.95%,汉族下降17.5%.这提示,藏族少年有较好的最大有氧能力及氧运输能力,显示对高原环境的最佳适应;无氧阈可能被成为评价高原劳动能力的较好指标.     

高原健康人运动状态下最大氧耗量无氧代射阈值及心功能…

在海拔３４１７ｍ地区测定了藏汉族少年的最大氧耗量及无氧代射阈。结果：最大耗氧量藏族大于汉族（Ｐ＜０．０５），无氧阈汉族低于藏族（Ｐ＜０．０１）。血氧饱和度随运动负荷的增加而下降，达到最大负荷时藏族下降８．９５％，汉族下降１７．５％。这提示，藏族少年有较最大有氧能力及氧运输能力，显示对高原环境的最佳适应；无氧阈可能被成为评价高原劳动能力的较好指标。     

海拔4 300 m世居藏族与移居汉族青年心血管X线对比观察

目的：探讨高原世居与移居两种不同人群对高原低氧环境的适应机理。方法：对海拔４３００ｍ的２５名世居藏族与２５名移居汉族青年拍摄正位Ｘ线胸片，测量心血管有关指标。结果：移居汉族青年较世居藏族青年心高径、心脏面积及升主动脉宽径显著增大和心胸比率相差显著（Ｐ〈０．０５），右心室高径、主脉动脉干横径、肺动脉段突出度、右下肺动脉宽径、主动脉结宽径、主动脉长径、胸廓横径及肺面积增大非常显著（Ｐ〈０．０１）。结论     

高原移居者与世居者心肺功能的比较研究

目的 :观察高原移居者与世居者心肺功能的异同 ,以探讨心肺功能在高原低氧习服-适应中的作用。方法 :在海拔 4 30 0m高原 ,以移居汉族和世居藏族青年各 2 5人为受试对象 ,用电子肺功能仪测定肺功能 (FVC、FEV1、MVV等 6项参数 ) ,用血氧饱和度仪测定血氧饱和度和心率。结果 :( 1)高原移居 1年与 2年者的用力肺活量 (FVC)分别为 ( 4 .2 8± 1.2 0 )L与 ( 4 .92±1.18)L ,1秒钟用力呼出量 (FEV1)分别为 ( 3.89± 1.0 4 )L与 ( 4 .16± 1.17)L ,最大通气量 (MVV)分别为 ( 2 88.90± 4 9.4 8)L与 ( 2 80 .36± 50 .84 )L ,都明显的低于高原世居者的 ( 17.33± 0 .90 )L、( 6.32± 1.16)L与 ( 319.76± 4 5.2 9)L。 ( 2 )高原移居者的心率明显高于高原世居者 ;移居高原 1年者的心率 ( 89.1± 7.9)b·min 1明显高于移居 2年者的心率 ( 80 .9± 11.0 )b·min 1,而后者又高于高原世居者 ( 71.2 +10 .2 )b·min 1。 ( 3)高原移居者与世居者的动脉血氧饱和度十分接近。结论 :在海拔4 30 0m停留 2年的移居者其心肺功能仍然没有达到高原世居者的水平。     

西藏自治区干部职工的睡眠质量及相关影响因素

目的了解西藏自治区干部职工的睡眠质量及相关影响因素。方法采用自行设计的问卷及匹茨堡睡眠质量指数量表(PSQI)对西藏7个地市的干部职工以随机整群抽样的方法进行自填式的问卷调查。采用SPSS 25.0软件进行数据分析,对一般情况进行描述性分析、对计量资料进行秩和检验,对多因素分析进行logistic回归分析。结果西藏自治区干部职工的平均PSQI得分为(6.45±3.31),低睡眠质量的检出率为32.82%,其中世居藏族中低睡眠质量的检出率为23.88%,移居汉族中低睡眠质量检出率为43.43%。世居藏族PSQI总分和7个部分的得分均低于移居汉族;在海拔3 500 m以上时,海拔越高睡眠质量越差。高原居民类型、年龄、地区及海拔对睡眠质量均有显著影响(P0.001),高原居住年限对睡眠质量有影响(P0.05),而性别对睡眠质量没有影响(P0.05)。结论西藏自治区干部职工的睡眠质量较国内平原地区居民差,世居藏族的睡眠质量普遍较移居汉族好。无论世居藏族还是移居汉族,随着年龄的增长睡眠质量均变差。移居汉族在高原居住年限越长睡眠质量越差,世居藏族并无这一规律。居住地区及海拔与睡眠质量有相关性。     

对高原缺氧环境下世居藏族和移居汉族胎儿脐动脉及大脑中动脉血流参数的研究

目的通过检测高原缺氧环境下高原人群(世居藏族和移居汉族)晚孕期胎儿脐动脉(UA)及和大脑中动脉(MCA)血流参数,绘出血流参数散点图,找寻其随孕周的变化规律。探讨高原缺氧环境下世居者(藏族)及移居者(汉族)胎儿UA及MCA血流参数的差异及意义。方法选取2017年10月-2019年6月青海省玉树地区(平均海拔3500 m以上)世居者组、移居者组(居住时间2年以上)及移居者组(居住时间2年以下)晚孕期产妇胎儿各30例,在进行常规超声检查后应用彩色多普勒超声诊断仪检测UA及MCA血流参数[血流速度峰谷比(S/D)、阻力指数(RI)、搏动指数(PI)],绘出血流参数散点图,比较晚孕期世居者组和移居者组胎儿血流参数随孕周变化情况,分析血流参数与孕周的关系;比较3组胎儿UA及MCA血流参数值,发现其两两之间是否存在差异,并分析高原缺氧环境与其差异的关系。结果高原缺氧环境下,世居者和移居者胎儿UA-S/D、UA-RI及UA-PI值与孕周呈负相关的线性图;MCA-S/D、MCA-RI及MCA-PI值在30周左右出现转折点,28~30周各参数值与孕周关系图呈上升趋势,30~40周各参数值与孕周关系图呈下降趋势。高原缺氧环境下,相同孕周段世居者组和移居者组(居住时间2年以上)胎儿UA和MCA血流参数值(S/D、RI、PI)均低于移居者组(居住时间2年以下),差异有统计学意义(P<0.05)。高原缺氧环境下,相同孕周段世居者组与移居者组(居住时间2年以上)胎儿UA和MCA血流参数值(S/D、RI、PI)相差甚少,差异无统计学意义(P>0.05)。结论高原缺氧环境下,世居者与移居者胎儿UA-S/D、UARI及UA-PI随着孕周增加而数值减低;世居者与移居者胎儿MCA-S/D、MCA-RI及MCA-PI值与孕周散点图似抛物线状,存在一个先上升后下降的过程。高原缺氧环境下,移居者(居住时间2年以下)胎儿UA及MCA血流参数值均高于世居者和移居者胎儿(居住时间2年以上),说明高原缺氧环境影响移居者(居住时间2年以下)胎儿宫内生长发育,移居汉族人群在居住的2年时间内还没有完全习服。在高原缺氧环境下,移居汉族人群居住时间超过2年以上,形成了类似世居藏族母体-胎盘-胎儿系统及适应低氧的胎盘机制,做到了完全习服。因此,高原缺氧环境下移居汉族孕产妇应充分做好保健来缩短高原习服的时间,为移居者围生期安全提供保障。     

大气污染对人体心肺功能的影响

目的探讨大气污染对健康人体心肺功能的危害。方法在污染较严重的地区选取15名健康成年人作为污染组(EG),同时在洁净区选取相同人群作为对照组(CG)。用国产台式血压计测量安静状态下动脉血压,FHL-Ⅱ型肺活量计测量安静肺活量。用意大利Cosmed公司生产的quark b2型运动心肺功能检测系统,对受试者递增负荷踏车运动过程中心肺功能水平进行测试。结果安静状态EG除心率(HR)高于、肺活量(VC)低于CG(P<0.01,P<0.05)外,其余指标两组间无显著差异。运动负荷量达到无氧阈(AT)状态时,摄氧量绝对值(VO2)、摄氧量相对值(VO2/kg)、氧脉搏(O2P)、代谢当量(METS)几项指标CG均显著高于EG(P<0.05,P<0.01)。运动负荷量达到最大摄氧量(VO2max)状态时,VO2max、最大摄氧量相对值(VO2max/kg)、O2P、METS、运动持续时间(DT)等指标CG均显著高于EG(P<0.01),但EG运动后心率恢复较CG缓慢。结论大气污染给人体心肺功能水平和储备能力均带来不良影响。动态心肺功能评价指标更能全面准确评价大气污染等不良因素对人体心肺功能的潜在危害。     

Blood pressure at rest and during exercise among Sherpas and Tibetan migrants in Nepal

Tibetan migrants living in an urban environment at low altitude show higher resting systolic blood pressures and more gradual increases in systolic blood pressure during exercise than do Tibetan migrants and Sherpas living at high altitude. Exercise differences are probably related to variations in activity pattern. Resting differences are probably not due to altitude or morphology; but are more likely associated with Western influences on diet and lifestyle.     

Effects of dynamic exercise on plasma arachidonic acid epoxides and diols in human volunteers

Metabolites of the cytochrome P450 (CYP) pathway may contribute to vasodilation of the vasculature. However, it is not known whether exercise affects their circulating concentrations. The authors determined effects of exercise intensity and duration on plasma concentrations of epoxy and dihydroxy metabolites of arachidonic acid. Their goal was to delineate the threshold workload, optimal workload, and duration required to produce increases in plasma concentrations of these vasoactive substances. Healthy volunteers (N = 14) performed maximal exercise testing on a bicycle ergometer during Visit 1. On separate days, subjects cycled for 20 min at 30%, 60%, and 80% of their maximal exercise intensity. The last day consisted of 40 min of exercise at 60% of maximal exercise intensity. Venous blood was obtained before, during, and after exercise for analysis. Compared with rest, increases were observed during the 80% workload at 20 min postexercise -14,15-DHET (0.77 ± 0.21 vs. 0.93 ± 0.27 nM) - and at 2 min postexercise: 11,12-DHET (0.64 ± 0.22 vs. 0.71 ± 0.24 nM; p < .05). Also compared with rest, 40-min values during the 60% workload were 14,15-DHET 0.79 ± 0.22 vs. 0.91 ± 0.31 nM and at 2 min post 14,15 EET 0.12 ± 0.06 vs. 0.21 ± 0.16 nM (p < .05). Results suggest the CYP metabolites (i.e., DHETs) are released during short-term high-intensity and long-term moderate-intensity exercise.     

The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists

The main objective of this research was to determine the effects of a long-term ketogenic diet, rich in polyunsaturated fatty acids, on aerobic performance and exercise metabolism in off-road cyclists. Additionally, the effects of this diet on body mass and body composition were evaluated, as well as those that occurred in the lipid and lipoprotein profiles due to the dietary intervention. The research material included eight male subjects, aged 28.3 ± 3.9 years, with at least five years of training experience that competed in off-road cycling. Each cyclist performed a continuous exercise protocol on a cycloergometer with varied intensity, after a mixed and ketogenic diet in a crossover design. The ketogenic diet stimulated favorable changes in body mass and body composition, as well as in the lipid and lipoprotein profiles. Important findings of the present study include a significant increase in the relative values of maximal oxygen uptake (VO_2max) and oxygen uptake at lactate threshold (VO₂ LT) after the ketogenic diet, which can be explained by reductions in body mass and fat mass and/or the greater oxygen uptake necessary to obtain the same energy yield as on a mixed diet, due to increased fat oxidation or by enhanced sympathetic activation. The max work load and the work load at lactate threshold were significantly higher after the mixed diet. The values of the respiratory exchange ratio (RER) were significantly lower at rest and during particular stages of the exercise protocol following the ketogenic diet. The heart rate (HR) and oxygen uptake were significantly higher at rest and during the first three stages of exercise after the ketogenic diet, while the reverse was true during the last stage of the exercise protocol conducted with maximal intensity. Creatine kinase (CK) and lactate dehydrogenase (LDH) activity were significantly lower at rest and during particular stages of the 105-min exercise protocol following the low carbohydrate ketogenic diet. The alterations in insulin and cortisol concentrations due to the dietary intervention confirm the concept that the glucostatic mechanism controls the hormonal and metabolic responses to exercise.     

Effects of acute (-)-hydroxycitrate supplementation on substrate metabolism at rest and during exercise in humans

BACKGROUND: (-)-Hydroxycitrate (HCA), a competitive inhibitor of ATP-citrate lyase, should reduce the extramitochondrial acetyl-CoA pool. It has been hypothesized that HCA ingestion can reduce malonyl-CoA concentrations and consequently increase fatty acid oxidation in vivo. OBJECTIVE: This study investigated the acute effects of HCA supplementation on substrate utilization at rest and during exercise in endurance-trained humans. DESIGN: Ten cyclists [x+/- SD) age: 24 +/- 2 y, weight: 73 +/- 2 kg, maximal oxygen uptake: 4.95 +/- 0.11 L/min, maximal work output (W:max): 408 +/- 8 W] were studied at rest and during 2 h of exercise at 50% W:max on 2 occasions. Both 45 and 15 min before exercise and 30 and 60 min after the start of exercise, 3.1 mL/kg body wt of an HCA solution (19 g/L) or placebo was ingested. Total fat and carbohydrate oxidation rates were assessed. Blood samples were collected at 15-min intervals at rest and every 30 min during exercise. RESULTS: Plasma HCA concentrations increased after HCA ingestion up to 0.39 +/- 0.02 mmol/L (82.0 +/- 4.8 mg/L). However, no significant differences in total fat and carbohydrate oxidation rates were observed between trials. Accordingly, plasma glucose, glycerol, and fatty acid concentrations did not differ between trials. Plasma lactate concentrations were significantly lower in the HCA than in the placebo trial after 30 min of exercise but at the end of the exercise period they did not differ between trials. CONCLUSION: HCA, even when provided in large quantities, does not increase total fat oxidation in vivo in endurance-trained humans.     

Migration and descent,adaptations to altitude and tuberculosis in Nepalis and Tibetans

BackgroundHigh rates of tuberculosis (TB) in migrants from Tibet and Nepal have been documented for over 120 years and were previously ascribed to poor living conditions in the places of settlement. Adaptations to altitude involving genes in the Hypoxia-Inducible Factor pathway are present in 90–95% of Tibetans and in Nepalis these allele frequencies increase by 17% with each 1000 m increase in altitude.MethodsWe calculated the incidence of TB by country of origin in immigrants from South and East Asia in New South Wales (NSW), Australia between 2004 and 2018, and compared disease severity, site of infection, evidence of local transmission and prevalence of latent TB, among these groups.ResultsThe incidence of active TB was consistently higher among 30 000 Nepalese and 1000 Tibetans than among all other immigrants to NSW. Nepal was the only country of origin where TB incidence in immigrants was not significantly lower than the reported TB incidence in the country of origin.Conclusions and implicationsHigh rates of TB among Nepalese and Tibetan immigrants in Australia are unlikely to be attributable to pre-existing disease or local acquisition. Phenotypic effects of high-altitude adaptations may include a dampening of inflammatory responses to hypoxia, an effect unmasked by descent to a normoxic environment. A corollary of these findings may be that hypoxia-induced inflammation limits TB progression, reconfirming previous explanations for the apparent efficacy of high-altitude sanatoria. If vindicated by subsequent research, these provisional findings could open new avenues into preventive and host-directed interventions for tuberculosis.Lay SummaryThe incidence of tuberculosis among Nepalese immigrants to Australia and other people of Tibetan heritage who migrate to lower altitudes is very high. In these screened populations, pre-existing active TB or locally acquired infection are unlikely explanations. We suggest that adaptations to altitude combined with descent to higher oxygen levels in air at sea level may be contributing factors.     

A scientific nutrition strategy improves time trial performance by ≈6% when compared with a self-chosen nutrition strategy in trained cyclists: a randomized cross-over study

We investigated whether an athlete's self-chosen nutrition strategy (A), compared with a scientifically determined one (S), led to an improved endurance performance in a laboratory time trial after an endurance exercise. S consisted of about 1000 mL·h(-1) fluid, in portions of 250 mL every 15 min, 0.5 g sodium·L(-1), 60 g glucose·h(-1), 30 g fructose·h(-1), and 5 mg caffeine·kg body mass(-1). Eighteen endurance-trained cyclists (16 male; 2 female) were tested using a randomized crossover-design at intervals of 2 weeks, following either A or S. After a warm-up, a maximal oxygen uptake test was performed. Following a 30-min break, a 2.5-h endurance exercise on a bicycle ergometer was carried out at 70% maximal oxygen uptake. After 5 min of rest, a time trial of 64.37 km (40 miles) was completed. The ingested nutrition was recorded every 15 min. In S, the athletes completed the time trial faster (128 vs. 136 min; p ≤ 0.001) and with a significantly higher power output (212 vs. 184 W; p ≤ 0.001). The intake of fluid, energy (carbohydrate-, mono-, and disaccharide), and sodium was significantly higher in S compared with A (p ≤ 0.001) during the endurance exercise. In the time trial, only sodium intake was significantly higher in S (p ≤ 0.001). We concluded that a time trial performance after a 2.5-h endurance exercise in a laboratory setting was significantly improved following a scientific nutrition strategy.     

Fatty acid profiles of blood lipids in a population group in Tibet: correlations with diet and environmental conditions

The aim of this study was to compare blood fatty acid profiles of two population groups: Italian and Tibetan, differing with regard to ethnic, life style and environmental aspects. Additionally the collection of two staple foods provided the opportunity to analyze typical Tibetan dishes. A new, simple, rapid, and substantially non invasive method for fatty acid (FA) analysis of blood lipids was applied to healthy Italian (n=14) and Tibetan (n=13) subjects. Blood drops obtained from the ear lobe of Tibetans or the fingertip of Italians were adsorbed by a special strip of paper and processed for fatty acid analysis. The fatty acid profiles of the two groups are different, and environmental factors, such as dietary fats and altitudes of Milan, Italy (a low altitude site), and Lhasa, Tibet (a high altitude site) appear to contribute to these differences. More specifically, in Ti-betans higher levels of monounsaturated fatty acids, including the 22 and 24 carbon molecules, were found. This appears to be derived mainly from locally consumed fats (mustard seed oil), and are associated with lower levels of total polyunsaturated fatty acids and higher levels of selected omega 3 fatty acids, when compared to the Italians. These relatively higher levels of monounsaturated fatty acids may also indicate means of adaptation to local prooxidant conditions. The observed differences in blood fatty acid profiles in Tibetans vs. Italians appear to result both from dietary factors and adaptation to local environmental conditions such as the high altitude of the Tibetan location.     

Effects of p-Synephrine during Exercise: A Brief Narrative Review

The p-synephrine is the principal phytochemical found in bitter orange (Citrus aurantium). This substance is widely included in dietary supplements for weight loss/body fat reduction due to its potential benefits of increasing fat oxidation. For years, p-synephrine-containing dietary supplements have been marketed without proper knowledge of their true effectiveness to enhance fat utilization, especially when combined with exercise. However, the effects of p-synephrine on fat oxidation during exercise have been investigated in the last few years. The aim of the current discussion is to summarize the evidence on the effects of p-synephrine intake on fat oxidation and performance during exercise. Previous investigations have demonstrated that the acute intake of p-synephrine does not modify running sprint performance, jumping capacity, or aerobic capacity. However, the acute intake of p-synephrine, in a dose of 2–3 mg/kg of body mass, has been effective to enhance the rate of fat oxidation during incremental and continuous exercise. This effect has been observed in a range of exercise workloads between 30% and 80% of peak oxygen uptake (VO_2peak). The p-synephrine has the ability to increase the maximal rate of fat oxidation during exercise of increasing intensity without affecting the workload at which maximal fat oxidation is obtained (Fatmax). The effect of p-synephrine on fat oxidation is normally accompanied by a concomitant reduction of carbohydrate utilization during exercise, without modifying the energy expended during exercise. The shifting in substrate oxidation is obtained without any effect on heart rate during exercise and the prevalence of adverse effects is negligible. Thus, the acute use of p-synephrine, or p-synephrine-containing products, might offer some benefits for those individuals seeking higher fat utilization during exercise at low to moderate intensities. However, more research is still necessary to determine if the effect of p-synephrine on fat oxidation during exercise is maintained with chronic ingestion, in order to ascertain the utility of this substance in conjunction with exercise programs to produce an effective body fat/weight loss reduction.     

模拟36.5m氮氧饱和潜水26昼夜对人体肺通气量和摄氧量的影响

本文报道了7名受试者饱和暴露于36.5m氮氧条件下26昼夜及60-75m空气巡潜时肺通气量和摄氧量的变化。结果表明:1.高压条件下,影响人体肺通气功能最重要的因素是气体密度升高所致的呼吸阻力变大,因此,最大呼气、吸气流速、最大通气量和时间肺活量均有显著的下降。2.在高压暴露时,由于体力负荷的通气量有显著减少,所以呼吸困难指数有明显的增加。3.高压暴露期间的静息摄氧量和二氧化碳产生量与海平对照值接近,而体力负荷的摄氧量有增加的趋势,体力负荷后第3分钟的摄氧量有显著增加。这表明体力负荷时的氧债量增加了。     

Endurance exercise training in the elderly: effects on cardiovascular function

Among many arguments for encouraging the maintenance of an active lifestyle into old age is that those who exercise regularly may anticipate a reduced risk of chronic disease. In earlier studies, because of insufficient training stimuli, no improvement in maximal oxygen consumption (VO(2)max) was observed in individuals over 60 years of age. However, in more recent studies, after sufficient training, the VO2max response of the older individual was the same as that in younger persons. It is well documented that maximal cardiac output is the main component of the age-related decline in VO(2)max. The underlying mechanisms of the impairment of maximal cardiac function and the beneficial effect of regular endurance exercise training are discussed in the present review.